MyBB Community Forums

Hi !
I have a important and bad problem about my forum.
When I view my forum with FireFox browser, for twice time when I want to view my forum in work offline mood, I can not view.
I tested it with some versions of this browser, this problem is available for all versions.
of course, I can view it with IE browser but this browser is not good (about speed).

It is not from version of MyBB because my forum version and this forum version is 1.6, but I can view Community.MyBB.Com site in work offline mood in my FireFox Browser.
It is not from web hosting because I can view other pages from my website (except forum pages) in work offline mood.
please help me and write a way to solve this problem. (how to view forum with FireFox browser?)

please answer this question very soon, I need it a lot.
thanks a lot.

You can only view the forums that were actually recorded when you were online last, in offline mode, however I have no idea why you'd want to try and visit sites in this mode.